qoute GregC

I played with the new split second unit this week on the timing run. With my OBD-2 unit, I found that the WOT timing is around 20 degrees, going to 25 at 6K. This is about the same as most all 4-5L cars. I set the timing retard high to see if it worked, while looking with a scope. All is great.
I have setup the unit for 1.5 degrees retard per pound boost. I will set the final air/fuel with the MAF conditioner when I get the new pulley.

What I did find out "please read" is that the 5L 11:1 engine starts to Detonate at 3psi if the air/fuel is 12:1 or higher. BE CAREFULL ALL!

what that means is that all of us with any type of blower DO need a FMU that increases fuel pressure, thus in turn lowering the A/R ratio in boost.

Most all the blower people will say a conservative is 11.5:1 A/F is ideal. If you feel good you can get 12-12.5 with race gas or methonal injection.

I hope to complete tuning sometime just after Christmas and get to the Dyno.

I can say that I am impressed/not impressed with the Powerdyne. The Powerdyne has a mush better boost curve than the Vortech and Procharger, which I have had in the past. It' still not a roots unit, but it has done well. I have found the the BD-11A unit is at about max RPM on a CLK55. IF,IF I am able to get 8psi with the new pulley will be a test. I am on the edge, as I must say I am impressed with the air flow abilities of the Mercedes 5.4L.

One more, to keep fuel pressure up with boost, as the FMU is supposed to do, requires I set the boost-a-pump to 25% increase in voltage. That is about 15 Volts. Since I am at about 75psi at full boost that means those pumps I found may work. You may be able to use a FMU and upgraded fuel pump in place of the kenne-bell boost-a-pump. I am still not 100% such with a system runnign 7-8psi boost.


I wish I could find a machine shop to make a bracket and 1-2 curved tubes. The cost of this system is not that much. I hate to see blower unit systems selling for $3-4K for all the other cars in the world, and the few that sell mercedes units charge 8-15K!!